Her Way Forward · Good to know

The line is 23

If your family background is South Asian, Black African or African Caribbean, the point at which you should be checked for type 2 diabetes is lower than the number most people are told, and it starts fifteen years earlier. Both of those are in the official guidance. Neither tends to come up.

Most of us have heard that a BMI of 25 is where a doctor starts paying attention. That figure was worked out mainly from the bodies of white Europeans. It does not describe risk accurately for everyone, and NICE, which writes the guidance GPs follow, sets a different line for some of us.

White European family background

25 Increased risk

South Asian, Chinese, Black African or African Caribbean family background

23 Increased risk

NICE public health guideline PH46. The higher band, where risk is described as high rather than increased, moves in the same way, from 30 down to 27.5.

Two points of BMI sounds like very little. It is not, because of where it sits. A woman at 24 has been on the safe side of the only number she was ever given, while sitting inside the band the guidance says should trigger a conversation.

Age matters more than the weight does

Diabetes UK puts it plainly. People from Black African, African Caribbean and South Asian backgrounds are at risk of developing type 2 diabetes from the age of 25. For the white population, risk starts climbing at 40.

Fifteen years. That is the part almost nobody mentions, and it matters more than the BMI number, because the free NHS Health Check is offered from 40. If your risk began at 25, the standard invitation arrives late.

This is about when to get checked. It is not a statement about what you should weigh, and it is not a reason to feel worse about your body. A threshold is a trigger for a blood test. Nothing more than that.

What you can actually ask for

At your GP surgery

You can ask for a diabetes risk assessment. You do not have to wait to be invited, and you do not need symptoms.

I have a South Asian family background. I understand the BMI threshold for diabetes risk is lower for me. Can I have a risk assessment?

It is usually a finger-prick or a blood test called HbA1c, which shows your average blood sugar over the past two or three months. If you are between 40 and 74 you can also ask for the free NHS Health Check, which covers this along with blood pressure and cholesterol.

In Wandsworth this is not a small gap. The borough’s own health plan estimates around 6,000 people have type 2 diabetes and do not know it, with a further 11,780 at high risk.

If you would rather not know

Worth saying, because it is usually the real reason a test gets put off. Being in the increased-risk band is not a diagnosis. It is the band the NHS Diabetes Prevention Programme exists for, and that programme exists because moving from increased risk to diabetes is not a foregone conclusion.

Knowing earlier gives you more room, not less.

Why we keep going on about walking

Type 2 diabetes is one of the few serious conditions where what you do in an ordinary week genuinely shifts the odds. Movement makes your body better at using insulin, which is the exact mechanism that goes wrong. It works whether or not you lose any weight at all.

It does not have to be a gym. Walking counts. Carrying shopping up the stairs counts. Our Fitwell classes run on Mondays and cost £5, and the Friday walks through Battersea Park are free. We bring the mats. Both are women only. Nobody watches you and nobody compares.

If the £5 is the thing standing in the way, say so when you message. There is no form and no proof needed for that, and we keep spots for it.

None of this means anyone is going to get diabetes. Plenty of women in the increased-risk band never do. It means the check is worth having earlier than you were told, and that the number you were measured against may not have been yours.

Where this comes from

Everything on this page comes from published guidance or official local data. You can check any of it yourself, and we would rather you did.

BMI thresholds of 23 and 27.5NICE public health guideline PH46, Type 2 diabetes: prevention in people at high risk. Sets lower BMI action thresholds for South Asian, Chinese, Black African and African Caribbean adults.
Risk from age 25 rather than 40Diabetes UK, Ethnicity and type 2 diabetes.
Around 6,000 undiagnosed and 11,780 at high risk in WandsworthWandsworth Health & Care Plan 2025–27, NHS South West London Integrated Care Board.
Lower BMI, equivalent riskEthnicity-specific BMI cutoffs for obesity based on type 2 diabetes risk in England, a population-based cohort study published in The Lancet Diabetes & Endocrinology, 2021.
Activity and insulin sensitivityNHS guidance on preventing type 2 diabetes, and the NHS Diabetes Prevention Programme.

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